Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

In Progress Releases

Note: The release notes on this page are for releases still under development. Please don't use this page as a source of information, it's here for development purposes only. Everything is subject to change.

Version 1.85.0

In Progress

New Libraries

  • Charconv: A high quality implementation of <charconv> in C++11, from Matt Borland.
  • Scope: A collection of scope guard utilities and a unique_resource wrapper, from Andrey Semashev.

Updated Libraries

  • Beast:
    • API Changes
      • The status code list has been updated to conform with the IANA registry.
    • Fixes
      • Unreachable code warning in buffers_cat.hpp.
      • Connection error handling in websocker_server_awaitable example.
      • Concurrent calls to async_write in advanced server examples.
      • zlib name conflicts with minizip.
      • host string should be updated after SSL_set_tlsext_host_name().
    • Improvements
      • asio::associator is specialized for bind_wrapper and bind_front_wrapper.
      • Add non-allocating overload for error category message function.
    • Documentation
      • Specifies when calling http::message::prepare_payload() is optional.
      • Operations affected by basic_stream::expires_after().
      • teardown() and async_teardown() are customization points.
      • Moving or copying http::serializer after first usage is undefined behaviour.
      • websocket::permessage_deflate should be configured before performing the WebSocket handshake.
      • bytes_transferred in http reads operations reports the number of bytes consumed by the HTTP parser.
    • Acknowledgements
      • Emile Cormier, JohannesWilde, yhzx233
  • Bind:
    • C++03 is no longer supported; a C++11 compiler is required. (This includes GCC 4.7 or later, and MSVC 12.0 (VS 2013) or later.)
  • Conversion:
    • Removed outdated mentions of boost::lexical_cast that is not part of the library any more. Thanks to Danil Sidoruk for the PR PR#28!
  • Function:
    • C++03 is no longer supported; a C++11 compiler is required. (This includes GCC 4.7 or later, and MSVC 12.0 (VS 2013) or later.)
  • JSON:
    • Boost.Endian is now used to deal with endianness.
    • Aliases to Boost.System and Boost.Container components are deprecated and will be completely removed in 1.87.0.
    • Conversion of described classes supports private members.
    • Rvalue reference overload for visit.
    • Add conversion support for path-like types.
    • Parsing into described classes correctly considers inherited members.
    • Conversion of self-referential sequences is disabled.
    • Fixed reference handling in visit.
  • LEAF:
    • New API for transporting of error objects and exceptions between threads: try_capture_all.
    • result<T> able to transport exceptions captured via try_capture_all.
    • result<T> transporting dynamically captured error objects with improved efficiency.
    • Old make_shared_context/capture APIs are deprecated, will be removed in the next release.
    • Removed support for transporting of dynamicaly captured error objects in exceptions.
  • LexicalCast:
    • Significant rewrite of the internal logic to separate optimized and C++ Standard Library IO-based streams:
      • C++ Standard Library based streams now constructed in less cases leading to better performance;
      • less template instantiations and simpler code;
      • always use std::char_traits (do not use custom traits from input/output types as it leads to linktime or runtime errors);
      • fixed missuse of forward declared boost::array (thanks to 13steinj for the report #64!);
      • support for volatile input types was dropped, following the C++ Standard Library trend.
    • Optimized conversions from std::basic_string_view and boost::basic_string_view #30.
    • Dropped dependency on Boost.NumericConversion and Boost.MPL. Fixed some cases of converting floting point types to arithmetics.
    • The library now compiles and works fine with -fno-sanitize-recover=integer #45.
  • Locale:
    • Fix linker issues due to missing typeinfo for char8_t in C++20 mode
    • Fix IConv compile flags when using ICU that has a bundled IConv
    • collator now throws on construction, if at all, as documented
    • collator no longer derives from std::collator to avoid possible type confusing when it isn't available for the current backend PR#216
    • Throw an exception when a faulty IConv library is detected (e.g. on some MacOS versions) instead of looping indefinitely PR#218
    • Reduce resolution of date_time to seconds as milliseconds where not easily available causing confusion #221
  • MSM:
    • Major Update. Backend update (back11). Requires C++ 11. The documentation now uses it as default.
    • Big new feature. New front-end (PlantUML). Requires C++ 20
    • Various Bugfixes (compiler errors and warnings, priority of deferred events)
  • Multi-index Containers:
    • Fixed documentation errors.
  • MySQL:
    • Breaking change: Boost.MySQL now requires linking to the new Boost.Charconv compiled library. This addresses a locale-dependency problem, increases efficiency, and powers the new client-side SQL formatting feature.
    • Added experimental support for connection pools, which allows re-using sessions and provides built-in reconnection and error handling.
    • Added experimental support for type-erased connections (any_connection class). any_connection is not a template and features simpler connection establishment and reconnection semantics.
    • Added experimental support for client-side SQL formatting functions (format_sql and format_sql_to). These allow securely composing queries client-side, which enables patterns like batch inserts, dynamic filters or PATCH-like updates.
    • Fixed a performance issue affecting close_statement and async_close_statement that could cause significant delays in application code.
    • Added support for building with BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT.
    • The deprecated execution interface (connection::query, connection::start_query, connection::execute_statement, connection::start_statement_execution and their async counterparts) now triggers warnings, as it's scheduled for removal in Boost 1.86.
    • Fixed a bug that caused some error messages to be truncated.
    • Warning cleanup. Builds are now clean from warnings when building with -Wall and -Wextra.
    • All field_view constructors are now stable.
    • The library internals have been rewritten using a sans-io approach to reduce complexity.
  • PFR:
    • boost::pfr::get_name now can work with local types on some compilers. Thanks to Bela Schaum for the PR PR#152!
    • Removed unused implementation details. Thanks to Denis Mikhailov for the PR PR#154.
    • Allow throwing exceptions from boost::pfr::structure_to_tuple. Thanks to Denis Mikhailov for the bug report #155.
    • Field reflection trick is now described in the docs. Thanks to all the discussion participans in #150!
  • System:
    • C++03 is no longer supported; a C++11 compiler is required. (This includes GCC 4.8 or later, and MSVC 14.0 (VS 2015) or later.)
    • The deprecated header boost/system/cygwin_error.hpp has been removed.
    • The original and obsolete (32 bit) MinGW is no longer supported. MinGW-w64 (both 64 and 32 bit) is still supported.
    • operator& now works for result<void> (by way of taking a nullary function.)
    • Added operator|= for result.
  • Stacktrace:
    • Big new feature: stacktrace from arbitrary exception. On some POSIX platforms std::stacktrace::from_current_exception() now returns the stacktrace of the current exception object as if the stacktrace was captures at the point of throwing the exception. Many thanks to Andrei Nekrashevich for prototyping the idea in libsfe.
    • Fixed memory consumption on Windows with boost_stacktrace_windbg. Thanks to ycyclop for reporting the issue #111, to Thiago A. Correa for providing more information, to Andrei Karpovskii for providing a possible fix.
    • Fixed library build with non hidden visibility. Thanks to Jan Bouwer for the report and information on how to fix it.
    • Added a separate section on async signal safety to the docs. Many thanks to tworonix for highlighting the problem in #131 and to itrofimow for information on the problem.
  • STLInterfaces:
    • Change the behavior of iterator_interface for input iterators in C++20 and later, to more closely follow the C++20 concepts.
    • Remove hidden friends from iterator_interface to fix errors about concepts being redefined with different constraints.
    • Add a new v3 inline namespace, containing a new iterator_interface based on deducing this instead of CRTP (C++23 and later).
    • Add an rvalue-qualified overload of closure::operator(), to prevent dangling temporaries.
  • Unordered:
    • Optimized emplace() for a value_type or init_type (if applicable) argument to bypass creating an intermediate object. The argument is already the same type as the would-be intermediate object.
    • Optimized emplace() for k,v arguments on map containers to delay constructing the object until it is certain that an element should be inserted. This optimization happens when the map’s key_type is move constructible or when the k argument is a key_type.
    • Fixed support for allocators with explicit copy constructors (PR#234).
    • Fixed bug in the const version of unordered_multimap::find(k, hash, eq) (PR#238).
  • Variant:
    • Removed more of the pre-C++11 macro and workarounds.

Updated Tools

Compilers Tested

Boost's primary test compilers are:

  • Linux:
    • Clang, C++03: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
    • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
    • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
    • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
    • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
    • GCC, C++03: 4.6.3, 11, 12
    • GCC, C++11: 4.7.3, 4.8.5, 11, 12
    • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
    • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
    • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
  • OS X:
    • Apple Clang, C++03: 11.0.3
    • Apple Clang, C++11: 11.0.3
    • Apple Clang, C++14: 11.0.3
    • Apple Clang, C++17: 11.0.3
    • Apple Clang, C++20: 11.0.3
  • Windows:
    • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

Acknowledgements

Marshall Clow and Glen Fernandes managed this release.